There are in the prior art many types of sockets made to fit into holes, including plated-through holes in printed circuit boards. Many of these small receptacles or sockets are comprised of two parts, one being an outer sleeve and the other being a contact spring within the sleeve as disclosed in U.S. Pat. No. 3,922,057. Because both a sleeve and a spring are required, the center line spacing between such mini-spring sockets is relatively large, of the order of 0.100 or more inches. Furthermore, the range of male terminal sizes which any given prior art small socket will take is relatively limited, being of the order of plus or minus 25% of the mid-range of terminal cross sections.
A further problem resides in the electrical connection of sockets to conductive paths on the substrate surface. Such a connection frequently is accomplished by soldering the lip of the socket sleeve to a conductive pad on the substrate or, alternatively, having the socket sleeve extend through the substrate for soldering to a conductive pad on the under surface of the substrate. However, certain risks exist in such a connection in that when a terminal post is inserted into a socket, strain is placed upon the solder connection causing occasional breakage and malfunction of the device.
A more recent development has been the use of conductive epoxy containing silver formed into circuit traces on the surface of the substrate. Prior to solidifying the epoxy adheres to the lip of a socket sleeve inserted in an aperture of the substrate. Again, however, the connection between the epoxy and the socket sleeve can break when a terminal is inserted into the socket.